Increased demand for mobile data has led to the use of smaller cells. Small cells may imply an increased spatial reuse of the same spectrum and may be a simple way to achieve higher capacity. Using low-power nodes may be a way to cope with an increase in mobile traffic, for example, for hotspot deployments in indoor and outdoor scenarios. A low-power node may be a node whose transmit power may be lower than a macro node or a base station (BS), e.g., pico or femto eNBs.
Increased demand for mobile data has also led to the use of additional spectrum, e.g., 3.5 GHz and higher frequencies. Large bandwidth channels may be available in high frequency carriers. With higher frequencies, a synergistic effect may be exploited, and spatial reuse may be increased relative to lower frequencies. Directional antennas (e.g., in wireless HD devices) may be used to close the link budget for millimeter wave (mmW) systems. Large bandwidth channels may make transmissions contained in that transmitted energy may be concentrated on the intended receiver (e.g., increasing signal strength) while radiating little in other directions, decreasing the likelihood of interference for unintended receivers. This may reduce the need for complicated inter-cell interference mitigation.
High frequency carriers (e.g., in the mmW spectrum) may have large amounts of available spectrum, possibly with affordable terms. The 60 GHz spectrum is about 7 GHz (e.g., depending on country), and more spectrum may become available as licensed, lightly licensed, or unlicensed spectrum.